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Vtx 1800c 2003 Misfiring.. aka missing.

7K views 28 replies 10 participants last post by  Mcgyevor 
#1 ·
Doing a repair and update on a New to me X. Bike is missing on the Front cylinder. In an attempt to resolve the issueI have replaced all plugs (DENSO IK 16 5303).... pulled the plug wires and exposed new inner conductor on the spark plug boot side... the issue remains. Additionally in the process of doing an oil change, I noticed the oil smelled slightly of gas...... anyone have additional input?


Thanks
 
#2 ·
#4 ·
Like Chuck said. Check the link for the FPR. It tells you how to test it. Also take a good look at your vacuum hoses. If the hose to your FPR looks these (like mine did) the FPR isn't doing its proper job even if it's been replaced.


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#5 ·
Checked the FPR as per the link.... pulled the Vacuum line no fuel present. Turned the fuel pump on .... I
no fuel coming from the vacuum port. According to the tests the FPR is good. However the vacuum lines are old and could stand to be replaced.

I
 
#7 ·
I will check that in the AM. When this began...I also noticed an increase in the engine noise. When this began...this noise comes and goes. Seemingly from the cylinder that is misfiring.

I attached a short video with audio. Again this noise began when the missing began and does come and go.
 
#10 ·
what do the spark plugs look like...

injector issues..
wiring for injectors.
do the coil/spark plug "spark" with them out of the bike.. test for spark

if spark.. its injector/fuel.. issue.

need to eliminate known good

air into cylinder
spark
fuel
compression.
exhaust

the basics... for an engine to run.
 
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#12 ·
what do the spark plugs look like...

injector issues..
wiring for injectors.
do the coil/spark plug "spark" with them out of the bike.. test for spark

if spark.. its injector/fuel.. issue.

need to eliminate known good

air into cylinder
spark
fuel
compression.
exhaust

the basics... for an engine to run

Spark present when plug removed....pics of plugs attached.
 

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#11 · (Edited)
I listened to your audio, it is muted.
I hear a recurring sound which is probably the de-compressor exhaust lobe.

When you pull the spark plugs and lay the shell of the spark plug on the cyl head do you see sparks at the gap when the engine is cranking????

Valkrider mentioned rubbing of insulation caused a coil wire to be Grounded.
If the Yellow/Blue or Blue/Yellow are grounded the coil is ON but a spark is only produced when the ECM releases a Ground.
Ground is the trigger, false ground from a short, true ground from a ECM, This scenario also has happened with Injectors.
Other times the ECM side (Trigger) has been grounded by shorting on a harness clip at the breakout at the Injector wires.

There have been a few cases where wires have shorted. A few times the the Black/White wire was shorted and blew the 30 amp FI fuse.
Remove the ECM connectors look for the wires going to the IGN coils(Yellow/Blue or Blue/Yellow) and the Injectors(Pink/Blue or Pink/Yellow)

With IGN switch ON, verify +12v on Black/White wires, then pulse a Ground on each Ignition coil and Injector.
You should see an arc at the spark plug, you should hear the injector click when energized.

Do both cylinders, all spark plugs out and shell Grounded.
NOTE:: When the Black/White wire has +12v on it, each coil and Injector will have that voltage on the ECM wire.
That is the first test for continuity through the coil or injector.

Do you have any FI error codes from the FI indicator?

What is the Autolite spark plug you are using???

Do you have a Service Manual??
 

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#13 ·
Put plugs on cylinder head all 4.... each plug fires when Engine is turned over.
Additionally the bike fired up and ran flawlessly for 5 minutes... the additional engine noise was gone... no misfires.... then after 5 minutes or so...Engine noise returned and it began to misfire?

No codes at all. Specifically no FI codes.
I replaced the original auto lite plugs with DENSO IRIDIUM PLUGS IK 16 5303.

I am downloading a service manual, currently.
 
#14 ·
Okay, latest update .... on black wire with white tracer out of the ECM... there is 12vdc with the ignition on. With the ignition on there is also 12 vbc on the pink wire with blue tracer and also on the pink wire with the yellow tracer. Momentary short to ground on either of the pink wires...does result in a click... injector reaction. It appears that spark is present at all four plugs as well. Any other suggestions?
 
#15 ·
Does it have a history of being parked for a long time??

It ran perfectly for five minutes..

Someone had an 1800, fine mesh screen
on injector had a blob of crap on it...

Something to think about...

Losing only one cylinder???

Another thing I mentioned earlier, where injector wires break out of the cable harness,
some shorts have occurred... Near a clip that holds the harness..
 
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#16 ·
Bike has sat up for several months. As I said I picked this bike up about a year ago. It ran just fine on the test ride and sounded good. However the bike was run down and as I began to work on it.... I began to realize the previous owner wasn’t exactly a Rocket Scientist. I have found countless wire splices... for God knows what reason. Today checking the injector function.... I found both the injector signal wires that been cut and sliced...??

However...it is always the front cylinder and there is no question the additional engine noise accompanies the misfire.
 
#21 ·
Does the bike have a fuel manager/tuner, like a PowerCommander? Those can go bad and dump enough fuel into the cylinder to make it miss - might also account for the fuel smell in the oil.

- steve
 
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#23 ·
Your plugs look like they are running rich (over fueling?) you say she ran for about five minutes then cut back to misfire? (is the front cylinder running at all? maybe check TPS (throttle position sensor) I had a bonnie which would die when warm turned out to be TPS not sure how V engines work but worth considering. My bet is over fueling you seem to have checked everything electrical and resolved any potential issues there. Also, check air filter for blockage, maybe being starved of air which will not help and would give running rich look to plugs.
 
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#26 ·
I am fairly certain the front cylinder is running some of the time...when it misfires there is an occasional flame out of the exhaust from the front cylinder. I might be reaching a bit here... but I think the front cylinder is running hotter. The chrome of the exhaust pipe (nearest the cylinder) appears to be developing a slight yellow tone. I have seen chrome do something similar when subjected to higher heat.

I think I might adjust the valves. I can bet it has never been done. Bike is a bit over 30K. Valve timing controls when fuel enters the cylinder and when the exhaust exits....
 
#27 ·
I have been contemplating doing the valve adjustment. I am willing to bet it hasn’t been done and the bike has over 30k in it. I will do that next. If nothing else’s it can be ruled out as a cause.
 
#25 ·
Additionally in the process of doing an oil change, I noticed the oil smelled slightly of gas...... anyone have additional input?


Thanks
Also, if the cylinder is missing, that raw fuel is going to blow by the rings, and end up in the oil, giving it that gassy smell. That fuel will thin out your oil too.
Hope this helps.
 

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#28 ·
Not to be a pia but,Any luck??
 
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